Members of this family known so far are catechol 1,2-dioxygenases of the Proteobacteria. They are distinct from catechol 1,2-dioxygenases and chlorocatechol 1,2-dioxygenases of the Actinobacteria, which are quite similar to each other and resolved by separate models. This enzyme catalyzes intradiol cleavage in which catechol + O2 becomes cis,cis-muconate. Catechol is an intermediate in the catabolism of many different aromatic compounds, as is the alternative intermediate protocatechuate. In Acinetobacter lwoffii, two isozymes are present with abilities, differing somewhat, to act on catechol analogs 3-methylcatechol, 4-methylcatechol, 4-methoxycatechol, and 4-chlorocatechol.